Spectrally sensitizing quick-processing photographic material

ABSTRACT

A LIGHT-SENSITIVE PHOTOGRAPHIC MATERIAL COMPRISING AT LEAST ONE SILVER HALIDE EMULSION LAYER, WHICH CONTAINS DEVELOPER SUBSTANCES AND IS SUITABLE FOR QUICK-PROCESSING, CAN BE SPECTRALLY SENSITIZED BY CERTAIN BENZIMIDAZOLE TRIMETHINE CYANINES.

United States Patent .6 Int. Cl. G03c 1/06, 1/18, 5/38 US. C]. 96-95 4 Claims ABSTRACT OF THE DISCLOSURE A light-sensitive photographic material comprising at least one silver halide emulsion layer, which contains developer substances and is suitable for quick-processing, can be spectrally sensitized by certain benzimidazole trimethine cyanines.

This invention relates to developer-containing quickprocessing photographic materials comprising at least one photosensitive silver halide emulsion layer which is spectrally sensitized by certain trimethine cyanine dyes.

It has long been known that the sensitivity of photosensitive layers, especially silver halide emulsion layers, can be increased by the addition of substances which broaden the spectral sensitivity range of the photosensitive substances. The sensitization of materials which are to be processed by modern quick-processing techniques, however, presents new problems due largely to the need for the materials to remain colorless in the White parts after processing whereas sensitizing dyes with hydrophilic substituents are frequently used to sensitize materials processed by conventional techniques, being leached out during processing by aqueous baths, such leachable dyes as these can only be used to a limited extent in quick-processing materials, because the quick-processing techniques, which often take only a few seconds, generally do not include a rinsing stage. For this reason, it is necessary to find a totally difl erent way of providing such quick-processing materials with the requisite photographic properties, such as high sensitivity, suitable gradation, adequate darkroom safety and adequate stability against heat or moisture, whilst guaranteeing that the layers remain completely colorless during processing.

It has now been found that trimethine cyanines corresponding to the general formula shown below sensitize silver halide emulsions with a very high level of intensity, retaining adequate darkroom safety, in addition to which they are compatible with other emulsion additives, especially developer substances, and finally, after quickprocessing, give completely colorless and speckle-free images. For this reason, they are eminently suitable for sensitizing quick-processing materials.

Accordingly, the invention relates to a developer-containing photosensitive photographic quick-processing material comprising at least one silver halide emulsion layer,

and a sensitizing dye corresponding to the general formula:

R R and R =identical or diflerent radicals, including:

hydrogen; halogen such as fluorine, chlorine or bromine; optionally substituted alkyl, for example methyl, trifluoromethyl or benzyl; alkenyl such as allyl; aryl, for example phenyl; OR, SR, SO-R, -SO' R,

SO -NR (R=hydrogen, alkyl or aryl); or thienyl);

R and.R =identical or different radicals, including: (1) alkyl or alkenyl with up to 4 carbon atoms, such as methyl, ethyl, isopropyl, propyl, butyl, isobutyl or allyl, optionally substituted by halogen, such as fluorine or chlorine, or by hydroxy, alkoxy, acyloxy, aryl such as phenyl, by acid radicals such as car-boxy, sulfo, sulfato, thiosulfato, phosphonic acid,

--SO NHCOR or SO NHSO R (R=alkyl or aryl) or by basic radicals such as dialkylamino, for example dimethylamino, pyrrolidinyl, piperidyl or morpholino, or the quaternary ammonium groups derived therefrom, for example --N+(CH C104; (2) cycloalkyl, such as cyclohexyl; or (3) aryl, for example phenyl; or one of the radicals R and R can be attached to the a-carbon atom of the trimethine chain, or to the carbon atom in the 4- or the 7-position of the benzimidazole group, to form an additional 5- or 6-membered ring;

R =-(1) alkyl or alkenyl with up to 4 carbon atoms, optionally substituted, for example by halogen such as fluorine or chlorine, hydroxy, alkoxy, acyloxy, aryl, carboxy, sulfo, sulfato or thiosulfato; (2) cycloalkyl, for example cyclohexyl; or (3) aryl, for example phenyl;

Z=the atoms required to complete an optionally substituted saturated 5- or 6-membered heterocyclic ring; preferred heterocyclic rings are those derived from thiazoline, selenazoline, pyrroline or tetrahydorpyridine; and

X6=any photographically inert anion, for example halide such as bromide or iodide, perchlorate, p-toluene sulfonate, alkyl sulfate, tetrafluoroborate, thiocyanate, nitrate, sulfate, phosphate, oxalate or acetate; X6 can be omitted when one of the radicals R to R contains an acid group in anionic form, so that a betaine is present.

The following dyes have proved to be particularly suitable for sensitizing quick-processing materials:

No. Dyestufl sens. 312:;

1 CH: Ca. 505

C1 Q N-- H:

e ulnar-mom) TABLE-Continued Sens. max. No. Dyestufi 01m.)

! lil l 01 CCH=CHGH=(} 0H,

(CH1): n'

as cm 513 HMS T son,

l C} o-oH=oHoH=( on,

$3 N (cm). 5

i H: H: N 0-0 I 5} CH: 1 O CCH=CHCH= H,

0-0 H, H, or 11, 5

60 (llz s 504 H3O -N s OH,

I I 1 01 /CCH CH-CH=C on,

i H300- -IiI s 0H 7 l 01 o-on=on on=o (3H,

N on. 5 s0.

V N no-orn-oms SCH1 I9 o-oH=oH-cH=o on, C1

In principle, dyes such as these are known as spectral sensitizers and are described, for example, in German patent specifications No. 700,781; 725,303; 728,043; 732,704 and 934,084. It was by no means predictable, however, that they would be compatible with developer substances in the large quantities in which these would normally be used in quick-processing materials, nor in particular was it predictable that materials containing these sensitizing dyes could be decolorized in the short processing time.

The sensitizing dyes can be used in any silver halide emulsions. Suitable silver halides include silver chloride, silver bromide, or mixtures thereof, optionally with a small silver iodide content of up to 5 mol percent. Silver chloride emulsions with a low silver bromide or silver iodide content are, however, preferred.

The silver halides can be dispersed in the usual hydrophilic binder compounds, for example in carboxymethyl cellulose, polyvinyl alcohol, polyvinyl pyrrolidone, alginic acid and its salts, esters or amides, or preferably in gelatin.

The sensitizing dyes used in accordance with the invention are preferably added to the photographic emulsion after chemical ripening and before casting. The methods used for this purpose are generally known to the expert. The sensitizing dyes are generally incorporated into the emulsion in solution in a water-soluble solvent, which must, of course, be compatible with the binder and should not have any adverse etfect upon the photographic properties of the emulsion. Water or alcohols, such as methanol or ethanol, or mixtures thereof, are generally preferred as solvents. The quantity of sensitizing dye added can be varied within wide limits, for example from 10 to 1000 mg. per mole of silver halide, preferably from 30 to 300 mg. per mole of silver halide. The concentration of the dye can be adapted to suit the requirements of the type of emulsion used, and the required sensitizing effect. The most suitable concentration for any given emulsion can readily be determined by the tests conventionally employed in photographic practice.

The hydroxyaryl compounds known as photographic developers, such as hydroquinone or pyrocatechol or derivatives thereof, can be used as developers in the quickprocessing materials according to the invention. The developers are preferably present in the photosensitive silver halide emulsion layer, although they can also be incorported in a layer of binder adjacent to the silver halide emulsion layer. The aforementioned developers are frequently mixed with other developer substances, for example with N-methylaminophenol or phenidone(1-phenyl- 19 3-pyrazolidone) or alkyl-substituted derivatives thereof, with which they are known to produce a synergistic etfect.

In order to protect the developers against oxidation by air, aldehyde/bisulfite or ketone/bisulfite addition compounds such as formaldehyde bisulfite or cyclohexanone bisulfite can also be added to the emulsion.

The emulsion can also be chemically sensitized, for example by the addition of sulfur-containing compounds during chemical ripening, for example allyl isothiocyanate, allyl thiourea and sodium thiosulfate. Other suitable chemical sensitizers include reducing agents, for example the tin compounds described in Belgian patent specifications No. 493,464 and 568,687, also polyamines such as diethylene triamine, or aminomethane sulfinic acid derivatives, for example in accordance with Belgian patent spectification No. 547,323.

Noble metals or noble metal compounds, such as gold, platinum, palladium, iridium, ruthenium or rhodium, are also suitable chemical sensitizers. This method of chemical sensitization is described in the article by R. Koslowsky in Z. Wiss. Phot. 46, 65-72 (1951).

The emulsions can also be chemically sensitized with polyalkylene oxide derivatives, for example with polyethylene oxide having a molecular weight of from 1000 to 20,000, and with condensation products of alkylene oxides and aliphatic alcohols, glycols, cyclic dehydration products of hexitols, alkyl-substituted phenols, aliphatic carboxylic acids, aliphatic amines, aliphatic diamines and amides. The condensation products have molecular weights of at least 700, preferably of more than 1000. In order to obtain special efiects, these sensitisers can, of course, be used in combination with one another, as described in Belgian patent specification No. 537,278, and in British patent specification No. 727,982. Quaternary ammonium salts can also be added to the emulsions as development accelerators.

The emulsions can contain the conventional stabilisers, for example homopolar or salt-like compounds of mercury with aromatic or heterocyclic rings, such as mercaptotriazoles, simple mercury salts, sulfonium mercury double salts and other mercury compounds.

Other suitable stabilizers include azaindenes, preferably tetraor penta-azaindenes, especially those of the kind substituted by hydroxy or amino groups. Compounds of the kind are described in the article by Birr in Z. Wiss. Phot. 47, 2-58 (1952). Other suitable stabilizers include inter alia heterocyclic mercapto compounds, for example phenyl mercaptotetrazole, quanternary benzthiazole derivatives and benztriazole. Heterocyclic mercapto compounds containing acid groups, of the kind described in German Auslegeschrift No. 1,151,731 are particularly suitable stabilizers. Compounds such as these can be used with particular advantage because they additionally are able to increase the spectral sensitivity provided by the dyestutfs used according to the invention to higher intensity.

The emulsions can be hardened in the usual way, for example with chromium salts or with organic hardening agents such as formaldehyde, glutaraldehyde, mucobromic acid or N,N', "-tris-acryloylhexahydro 1,3,5 triazine divinyl sulphone. In some instances, it is even possible to use several hardening agents in combination with one another.

The emulsions of the quick-processing materials according to the invention can also contain further additives, for example pla-sticisers, wetting agents such as saponin, nonionic alkyl ethylene oxide compounds or fiuoroalkyl sulphonic acids, or white toners, for example salts of bis- (triazinylamino)-stilbene sulfonic acids, and gelatin substitutes such as polyvinyl alcohol, styrene/maleic acid polymers, polyvinyl pyrrolidone and polyacrylamides.

In the following examples, all percentages are by weight, unless otherwise undealed.

20 EXAMPLE 1 20 mg. of dyestufi No. 1, dissolved in methanol 1:2000, are added with vigorous stirring to 1 kg. of a silver chloride emulsion containing 0.2 mole of silver of which 1.8 mol percent is in the form of silver bromide. Thereafter, 1.6 ml. of a 1% aqueous solution of the sodium salt of 2-mercapto-7-sulfonaphtho-[3,2-d]-oxazole and 2.5 ml. of a 1% methanolic solution of l-phenyl-S-mercaptotetrazole are stirred in 40 ml. of a 43% aqueous solution of the sodium salt of formaldehyde bisulfite, 17.5 g. of hydroquinone, 2 ml. of a 30% aqueous formaldehyde solution, 20 mi. of a 10% aqueous saponin solution and 10 ml. of a 10% aqueous solution of the sodium salt of 2,2 disulfo 4,4'-bis-[4-methoxyethylamino-6-(3'-sulfophenylamino)-2-triazinylamino]-stilbene (white toner), are also added. The mixture is digested for 20 minutes at 40 C. and then applied by dip-coating to a photographic baryta paper. The quantity of silver applied is 1.3 g./m.

Exposure in a spectral apparatus gives an excellent sensitization curve in the blue-green region of the spectrum with a maximum at approximately 505 nm.

Outstanding darkroom safety results from a fairly steep drop towards longer wavelengths. A speckle-free white image is obtained after quick development. Quick development is carried out in a standard apparatus using activator and stabilizer baths with the following compositions:

Activator:

60 g. of sodium hydroxide, 50 g. of anhydrous sodium sulfite, and 2 g. of potassium bromide,

made up with water to 1000 ml.

Stabilizer:

250 g. of ammonium thiocyanate, g. of sodium metabisulfite, and 20 g. of sodium acetate,

made up with water to 1000 ml. adjusted to pH 4.8 with acetic acid.

The activator bath has a contact time of 2 seconds, and the stabilizer bath has a contact time of 10 seconds.

EXAMPLE 2 14 mg. of dyestuff No. 3 dissolved in 28 ml. of methanol are added to 1 kg. of a silver bromide emulsion containing 0.18 mole of silver of which 1.2 mol percent is in the form of silver iodide. Thereafter 2 ml. of a 5% solution of N-phenyl N benzotriazolyl-(5)-urea in dimethyl formamide, 15 ml. of 10% aqueous saponin solution, 2 ml. of 30% aqueous Formalin solution, 20 g. of hydroquinone and 20 ml. of a 43% aqueous solution of formaldehyde sodium bisulfite, are added. The emulsion is cast on to paper to give a silver coating of 1.5 g. of silver/111. A protective layer containing 30 g. of gelatin and ml. of a 5% methanolic solution of phenidone per litre, is then cast over the emulsion.

Processing is carried out as in Example 1. The sensitization maximum is at 510 nm. The processed paper is spotlessly white.

EXAMPLE 3 1 kg. of a silver chloride bromide emulsion containing 0.26 mole of silver of which 58 mol percent is in the form of silver bromide, is stirred with 20 mg. of dyestufr No. 3 dissolved in 40 ml. of methanol. The following are also added: 22 g. of hydroquinone, 3 ml. of a 1% methanolic solution of l-phenyl-5-mercaptotetrazole, 20 m1. of 10% aqueous saponin solution and 70 ml. of a 2% aqueous solution of the white toner mentioned in Example 1.

The silver coating, protective layer, processing and quality are all as in Example 2.

EXAMPLE 4 20 mg. of dyestuff No. 1 and, optionally, the additives mentioned in the following table are added to samples of the emulsion described in Example 1. Thereafter, 40 ml. of a 43% aqueous solution of formaldehyde bisulfite, 17.5 g. of hydroquinone and 20 ml. of 10% aqueous saponin solution are added, per 1 kg. of emulsion. A paper coated with this emulsion gives the following sensitivity stages 3 days at 40 C. 82 Fresh humidity No addlt1on.. 16 11 16 mg. A 19 15 16. 5 18. 6 19 13 14 14 9 9 8 N0'rn.A=S0dium salt of d]-oxu.zole; B=Pheny1 mercaptotetrazole; C=White toner of Example 1 (stilbene derivative).

2-mercapto-7-sulfonaphtho- [3,2-

In the presence of the additives described in Example 4 (40 ml. of a 43% aqueous solution of formaldehyde bisulfite, 17.5 g. of hydroquinone and 20 ml. of a 10% aqueous saponin solution), 20 mg. of dyestuff No. 14 per kg. of the emulsion mentioned in Example I produce a spectral sensitization in the blue-green with a sensitization maximum at around 507 nm. The overall sensitivity obtained amounts to 22 stages After storage for 2 days under tropical conditions at 40 C./82% relative humidity, it falls to 13 stages, accompanied by serious fogging. When 60 mg of the sodium salt of Z-mercapto 8 sulfonaphth-[1,2-d]-oxazole (in aqueous solution) are added, the overall sensitivity after storage under tropical conditions is 21 stages and there are no signs of fogging.

What is claimed is:

1. A developer-containing photosensitive photographic quick-processing material which comprises at least one silver halide emulsion layer and a sensitising dyestufl of the formula:

in which R R and R =identical or different radicals, including hydrogen, halogen, alkyl, alkenyl, aryl, OR, SR, --SOR, -S0 --R, CO-R, COOR, CN, CONR -SO NR (R=hydrogen, alkyl or aryl), or thienyl;

R and R =identical or different radicals, including alkyl, alkenyl, cycloalkyl or aryl; or one of the radicals R and R can be attached to the a-carbon atom of the trimethine chain or to the carbon atom in the 4- or 7-position of the benzimidazole group to form an additional 5- or 6-membered ring;

R =alkyl, alkenyl, cycloalkyl or aryl;

Z=the atoms required to complete saturated 5 or 6- membered heterocyclic ring selected from the group consisting of thiazoline, selenazoline pyrroline and tetrahydropyridine; and

X =an anion, which can be omitted when one of the radicals R to R contains an acid group in anionic form, so that a betaine is present.

2. A photographic quick-processing material as claimed in claim 1 which contains hydroquinone as the developer.

3. A photographic quick-processing material as claimed in claim 1 which in addition contains a heterocyclic mercapto compound with an acid group as stabiliser.

4. A photographic quick-processing material as claimed in claim 1 which contains a white toner.

References Cited UNITED STATES PATENTS 2,256,163 9/1941 Kumetat et al. 96-137 3,264,110 8/1966 Depoorter et a1. 96138 3,380,828 4/1968 Kitce et a1 96-95 3,428,455 2/1969 Kitze 96137 3,660,102 5/1972 Riester 96-137 3,663,211 5/1972 Yao 96-138 J. TRAVIS BROWN, Primary Examiner M. F. KELLEY, Assistant Examiner US. Cl. X.R.

73330 UNIT'ED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. Date April 197? Inventor(s) oskar ester et al It. is certified that error appears in the above -identified patent and that said Letters Patent are hereby corrected as shown below:

Column 13, Formula '45, the benzimidazole ring should read as follows:

(?(JOCH Column 13, Formula 48, the right hand heterocyclic ring should read as follows:

Column 15, Formula &9, the right hand heterocyclic ring should read as follows:

Patent No. 3,726,68'4- Dated April 10, 1973 Inventors Oskar Riester et al Page 2 Column 15, Formula. 50, the right hand heterocyclic ring should read as follows:

Column 15, Formula 51, the right hand heterocyclic ring should read as follows:

Column 15, Foz mula 53, the benzimidazole ring should read as follows:

Column 15, Formula 55, the right hand ring should read as follows:

Signed and sealed this 16th day of July 1974 (SEAL) fattest:

MCCOY GIBSQN, JR. C. MARSHALL DANN Attestlng Offlcer Commissioner of Patents 

